December 1997 arXiv papers — page 5

Trevor W. Marshall

We develop a local realist analysis of parametric down conversion, based on the recognition that the pump field, instead of down converting spontaneously, does so through its nonlinear coupling with a real zeropoint, or "vacuum" electromagnetic field. The theory leads tothe prediction of a new phenomenon - that, in addition to the main down-conversio

Christian Krattenthaler

We compute the number of perfect matchings of an $M\times N$ Aztec rectangle where $|N-M|$ vertices have been removed along a line. A particular case solves a problem posed by Propp. Our enumeration results follow from certain identities for Schur functions, which are established by the combinatorics of nonintersecting lattice paths.

D. Minic

The concept of infinite statistics is applied to the analysis of black hole thermodynamics in Matrix Theory. It is argued that Matrix Theory partons, D0-branes, satisfy quantum infinite statistics, and that this observation justifies the recently proposed Boltzmann gas model of Schwarzschild black holes in Matrix Theory.

Oleg Kechkin, Maria Yurova

We show that the D=5 dilaton-axion gravity compactified on a 2-torus possesses the SL(4,R)/SO(4) matrix formulation. It is used for construction of the SO(2,2)-invariant BPS solution depended on the one harmonic function.

M. M. Sheikh-Jabbari

In this article, applying different types of boundary conditions; Dirichlet, Neumann, or Mixed, on open strings we realize various new brane bound states in string theory. Calculating their interactions with other D-branes, we find their charge densities and their tension. A novel feature of $(p-2,p)$ brane bound state is its "non-commutative" nature

C. Weiss

We review recent progress in calculating the twist--2 parton distribution functions at a low normalization point in the large--$N_c$ limit, where the nucleon can be described as a soliton of the effective chiral lagrangian. This field-theoretic approach preserves all general requirements on the distribution functions (positivity, normalization etc.). In part

C. Balazs, E. L. Berger, S. Mrenna, C. -P. Yuan

The production rate and kinematic distributions of isolated photon pairs produced in hadron interactions are studied. The effects of the initial-state multiple soft-gluon emission to the scattering subprocesses q-qbar, qg, and gg to gamma gamma X are resummed with the Collins-Soper-Sterman soft gluon resummation formalism. The effects of fragmentation photon

E. Tsitsishvili, Y. Levinson

We consider the influence of spin effects on the inter-Landau level electron-electron scattering rate in a two-dimensional electron gas. Due to the exchange spin splitting, the Landau levels are not equidistant. This leads to the suppresion of Auger processes and a nonlinear dependence of the lifetime on the concentration of the excited electrons even at ver

David A. Egolf, Joshua E. S. Socolar

We study a 1D ring of diffusively coupled logistic maps in the vicinity of an unstable, spatially homogeneous fixed point. The failure of linear controllers due to additive noise is discussed with the aim of clarifying the failure mechanism. A criterion is suggested for estimating the noise level that can be tolerated by the given controller. The criterion i

J. P. Zbilut, A. Giuliani, C. L. Webber,

Recurrence plots were introduced to help aid the detection of signals in complicated data series. This effort was furthered by the quantification of recurrence plot elements. We now demonstrate the utility of combining recurrence quantification analysis with principal components analysis to allow for a probabilistic evaluation for the presence of determinist

C. Alard, R. H. Lupton

We present a new method designed for optimal subtraction of two images with different seeing. Using image subtraction appears to be essential for the full analysis of the microlensing survey images, however a perfect subtraction of two images is not easy as it requires the derivation of an extremely accurate convolution kernel. Some empirical attempts to fin

G. Ghisellini

BeppoSAX observations of Mkn501 in April 1997 (Pian et al. 1998), have revealed an extraordinary X-ray emission from this BL Lac object, during a phase of high activity at TeV energies, as monitored with the Whipple, HEGRA and CAT Cerenkov telescopes. The 0.1-200 keV spectrum was hard, and the X-ray power output peaked at or above 100 keV, 2 or 3 orders of m

G. Ghisellini, G. Tagliaferri, L. Costamante, L. Maraschi

We report on the BeppoSAX observations of the gamma-ray blazar PKS 0528+134 performed in Feb and Mar 1997, during a multiwavelength campaign involving EGRET and ground based telescopes. The source was in a faint and hard state, with energy spectral index alpha=0.48+-0.04 between 0.1 and 10 keV, and [2-10] keV flux of 2.7E-12 erg/cm2/s. No significant variabi

Ron Donagi, Ron Livne

Computation of Gauss's arithmetic-geometric mean involves iteration of a simple step, whose algebro-geometric interpretation is the construction of an elliptic curve isogenous to a given one, specifically one whose period is double the original period. A higher genus analogue should involve the explicit construction of a curve whose jacobian is isogenous

Allen Hatcher, Darryl McCullough

The main theorem shows that if M is an irreducible compact connected orientable 3-manifold with non-empty boundary, then the classifying space BDiff(M rel dM) of the space of diffeomorphisms of M which restrict to the identity map on boundary(M) has the homotopy type of a finite aspherical CW-complex. This answers, for this class of manifolds, a question pos

Konrad Banaszek

We present a method for reconstructing the photon number distribution from the homodyne statistics based on maximization of the likelihood function derived from the exact statistical description of a homodyne experiment. This method incorporates in a natural way the physical constraints on the reconstructed quantities, and the compensation for the nonunit de

Patrick Dorey, Andrew Pocklington, Roberto Tateo, Gerard Watts

We study the spectrum of the scaling Lee-Yang model on a finite interval from two points of view: via a generalisation of the truncated conformal space approach to systems with boundaries, and via the boundary thermodynamic Bethe ansatz. This allows reflection factors to be matched with specific boundary conditions, and leads us to propose a new (and non-min

A. Doliwa, P. M. Santini, M. Manas

Motivated by the classical studies on transformations of conjugate nets, we develop the general geometric theory of transformations of their discrete analogues: the multidimensional quadrilateral lattices, i.e. lattices x: Z^N -> R^M, whose elementary quadrilaterals are planar. Our investigation is based on the discrete analogue of the theory of the rectilin

Vadim Schechtman

Givental's recursion relations for the flag varieties $G/B$ are established.

D. Vretenar, G. A. Lalazissis, P. Ring

Ground-state properties of spherical even-even nuclei $14\leq Z \leq 28$ and $N=18,20,22$ are described in the framework of Relativistic Hartree Bogoliubov (RHB) theory. The model uses the NL3 effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite range Gogny interaction D1S. Binding energies,

Tatsuo Suzuki

In this paper we introduce the $(n+2)$-dimensional Born-Infeld action with a dual field strength $\tilde{H}$. We compute the field equation by using Schur polynomials and give a soliton solution.

Sreerup Raychaudhuri

The excess in high-Q^2 events at HERA is introduced and possible explanations within the framework of R-parity violating supersymmetry are discussed.

J. Nemchik, N. N. Nikolaev, E. Predazzi, B. G. Zakharov

We develop the color dipole gBFKL phenomenology of a diffraction cone for photo- and electroproduction $γ^{*}N \to VN$ of heavy vector mesons (charmonium & bottonium) at HERA and in fixed target experiments. We predict a substantial shrinkage of the diffraction cone from the CERN/FNAL to the HERA range of c.m.s. energy $W$. The $Q^{2}$-controlled selectivity

Esteban Roulet, Laura Covi, Francesco Vissani

We study the CP asymmetries in lepton number violating two body scattering processes and show explicitly how they vanish, in agreement with unitarity constraints. We relate these cross section asymmetries to the CP decay rate asymmetries of the intermediate massive neutrinos and show how the inclusion of the Universe expansion via Boltzmann equations is the

Bartholomeus P. G. Mertens, Andreas S. Kronfeld, Aida X. El-Khadra

We address the perturbative renormalization of massive lattice fermions. We derive expressions-valid to all orders in perturbation theory and for all values of the bare fermion mass-for the rest mass, the kinetic mass, and the wave-function renormalization factor. We obtain the fermion's self energy at the one-loop level with a mass-dependent, $O(a)$ imp

Friedrich Knop

We consider a connected compact Lie group K acting on a symplectic manifold M such that a moment map m exists. A pull-back function via m Poisson commutes with all K-invariants. Guillemin-Sternberg raised the problem to find a converse. In this paper, we solve this problem by determining the Poisson commutant of the algebra of K-invariants. It is completely

Yurii A. Neretin

Consider a lattice $Γ$ in a group $G = SL_2(\R), SO(1,n), SU(1,n)$, $SL_2(\Q_p)$. We discuss actions of $Γ$ by affine isometric transformations of Hilbert spaces. We show that for irreducible affine isometric action of $G$ its restriction to $Γ$ is irreducible. We prove the existence of canonical irreducible affine isometric actions of $Γ$ associated to acti

M. I. Salkola, J. R. Schrieffer

Collective, low-energy excitations in quasi-two-dimensional d-wave superconductors are analyzed. While the long-range Coulomb interaction shifts the charge-density-wave and phase modes up to the plasma energy, the spin-density-wave excitation that arises due to a strong local electron-electron repulsion can propagate as a damped collective mode within the su

A. Bulatov, A. Kuklov, B. E. Vugmeister, H. Rabitz

We analyze a stimulated revival (echo) effect for the breathing modes of the atomic oscillations in optical lattices. The effect arises from the dephasing due to the weak anharmonicity being partly reversed in time by means of additional parametric excitation of the optical lattice. The shape of the echo response is obtained by numerically simulating the equ

Shan-Ho Tsai

We calculate the large-$q$ series expansion for the ground state degeneracy (= exponent of the ground state entropy) per site of the $q$-state Potts antiferromagnet on the $(3 \cdot 12^2)$ lattice, to order $O(y^{19})$, where $y=1/(q-1)$. We note a remarkable agreement, to $O(y^{18})$, between this series and a rigorous lower bound derived recently.

P. Soffitta, J. A. Tomsick, B. A. Harmon, E. Costa

We identify the periodic transient hard X-ray source GRO J1849-03 with the transient x-ray pulsar GS 1843-02 = X1845-024 based on the detection of x-ray outbursts from X1845-024 coincident with hard x-ray outbursts of GRO J1849--03. Based on its spin period of 94.8 s and its orbital period of 241 days, we classify the system as a Be/X-ray binary.

Anatoly Klypin, Stefan Gottlober, Gustavo Yepes

Formation of luminous matter in the Universe is a complicated process, which includes many processes and components. It is the vastly different scales involved in the process (from star formation on few parsec scales to galaxy clusters and superclusters on megaparsecs scales) and numerous ill-understood processes, which make the whole field a maze of unsolve

Scott Burles, David Tytler

We present our measurements of the deuterium to hydrogen ratio (D/H) in QSO absorption systems, which give D/H = 3.40 $\pm 0.25 \times 10^{-5}$ based on analysis of four independent systems. We discuss the properties of two systems which provide the strongest constraints on D/H. We outline the systematic effects involved in measurements of D/H and introduce

Ken Kiers, Michel H. G. Tytgat

It has recently been argued that long range forces due to the exchange of massless neutrinos give rise to a very large self-energy in a dense, finite-ranged, weakly-charged medium. Such an effect, if real, would destabilize a neutron star. To address this issue we have studied the related problem of a massless neutrino field in the presence of an external, s

N. Kumar, T. P. Pareek, A. M. Jayannavar

Recently we had proposed a mechanism for the normal-state C-axis resistivity of the high-T$_c$ layered cuprates that involved blocking of the single-particle tunneling between the weakly coupled planes by strong intra-planar electron-electron scattering. This gave a C-axis resistivity that tracks the ab-plane T-linear resistivity, as observed in the high-tem

Seungoh Ryu, David Stroud

We have numerically studied the statics and dynamics of a model three-dimensional vortex lattice at low magnetic fields. For the statics we use a frustrated 3D XY model on a stacked triangular lattice. We model the dynamics as a coupled network of overdamped resistively-shunted Josephson junctions with Langevin noise. At low fields, there is a weakly first-o

D. Atkinson, J. C. R. Bloch

A recent claim that in quantum chromodynamics the gluon propagator vanishes in the infrared limit, while the ghost propagator is more singular than a simple pole, is investigated analytically and numerically. This picture is shown to be supported even at the level in which the vertices in the Dyson-Schwinger equations are taken to be bare. The running coupli

R. Kirschner, L. Szymanowski

We study the next-to-leading gluon exchange in the high-energy scattering that contributes to the amplitude to order $s^0$ up to logarithmic corrections. Similar to the leading gluon exchange these contribution can be described in terms of reggeon exchanges. There are several gluonic reggeons at the next-to-leading level. Some of them transfer parity or gaug

Ariel Dobry, David Ibaceta

We study a model of a Spin-Peierls material consisting of a set of antiferromagnetic Heisenberg chains coupled with phonons and interacting among them via an inter-chain elastic coupling. The excitation spectrum is analyzed by bosonization techniques and the self-harmonic approximation. The elementary excitation is the creation of a localized domain structur

Alexander Khodjamirian

The method of light-cone QCD sum rules is applied to the calculation of the form factors of $γ^*ρ\to π$ and $γ^*γ\to π^0$ transitions. We consider the dispersion relation for the $γ^*(Q^2)γ^*(q^2) \to π^0$ amplitude in the variable $q^2$. At large virtualities $q^2$ and $Q^2$, this amplitude is calculated in terms of light-cone wave functions of the pion. As

Klaus Dietz, Michael Proebsting

We discuss electron-positron pair-production by super-intense, short laser pulses off the physical vacuum state locally deformed by (stripped) nuclei with large nuclear charges. Consequences of non-perturbative vacuum polarisation resulting from such a deformation are shortly broached. Production probabilities per pulse are calculated.

Suhyoung Choi

An affine manifold is a manifold with torsion-free flat affine connection. A geometric topologist's definition of an affine manifold is a manifold with an atlas of charts to the affine space with affine transition functions; a radiant affine manifold is an affine manifold with holonomy consisting of affine transformations fixing a common fixed point. We

D. Kabat, W. Taylor

We show that the linearized supergravity potential between two objects arising from the exchange of quanta with zero longitudinal momentum is reproduced to all orders in 1/r by terms in the one-loop Matrix theory potential. The essential ingredient in the proof is the identification of the Matrix theory quantities corresponding to moments of the stress tenso

M. Adler, P. van Moerbeke

The purpose of this paper is to study Toda-Darboux transforms, i.e., Darboux transforms for operators L(t) flowing according to the Toda lattice. Each element of the null-space $L(t)-z$ specifies a factorization for all t and thus a Toda-Darboux transform on $L(t)$. The Toda-Darboux map induces a transformation on the tau-vectors, given by a certain vertex o

M. Adler, E. Horozov, P. van Moerbeke

Let KdV stand for the Nth Gelfand-Dickey reduction of the KP hierarchy. The purpose of this paper is to show that any KdV solution leads effectively to a solution of the q-approximation of KdV. Two different q-KdV approximations were proposed, one by Frenkel and a variation by Khesin et al. We show there is a dictionary between the solutions of q-KP and the

M. J. Martins, P. B. Ramos

This work is concerned with various aspects of the formulation of the quantum inverse scattering method for the one-dimensional Hubbard model. We first establish the essential tools to solve the eigenvalue problem for the transfer matrix of the classical ``covering'' Hubbard model within the algebraic Bethe Ansatz framework. The fundamental commutati

David H. Sattinger, Jacek Szmigielski

\We consider an inverse scattering problem for Schrödinger operators with energy dependent potentials. The inverse problem is formulated as a Riemann-Hilbert problem on a Riemann surface. A vanishing lemma is proved for two distinct symmetry classes. As an application we prove global existence theorems for the two distinct systems of partial differential equ

John Preskill

The discovery of quantum error correction has greatly improved the long-term prospects for quantum computing technology. Encoded quantum information can be protected from errors that arise due to uncontrolled interactions with the environment, or due to imperfect implementations of quantum logical operations. Recovery from errors can work effectively even if

Tristan Hübsch

The measurement conundrum seems to have plagued quantum mechanics for so long that impressions of an inconsistency amongst its axioms have spawned. A demonstration that such purported inconsistency is fictitious may then be in order and is presented here. An exclusion principle of sorts emerges, stating that quantum mechanics cannot be simultaneously linear

F. Brosens, J. T. Devreese, L. F. Lemmens

We demonstrate analytically that a Bose-Einstein condensate confined in a harmonic trap with zero-range attractive interparticle interactions is unstable if there is more than 1 boson. Replacing the zero-range interaction by a short-range attractive interaction lifts the instability, and leads to a pronounced clustering, by which the particles leak out of th

M. Murao, M. B. Plenio, S. Popescu, V. Vedral

Purification schemes for multi-particle entangled states cannot be treated as straightforward extensions of those for two particles because of the lack of symmetry they possess. We propose purification protocols for a wide range of mixed entangled states of many particles. These are useful for understanding entanglement, and will be of practical significance

Ori Hay, Asher Peres

A measuring apparatus is described by quantum mechanics while it interacts with the quantum system under observation, and then it must be given a classical description so that the result of the measurement appears as objective reality. Alternatively, the apparatus may always be treated by quantum mechanics, and be measured by a second apparatus which has suc

Henry P. Stapp

William Unruh has suggested (quant-ph/9710032) that a certain counterfactual statement in my recent nonlocality proof should be re-interpreted in a way that would block the proof. I give reason's why that statement should not be re-interpreted.

Greg Kuperberg

We discuss the consequences of the possibility that Vassiliev invariants do not detect knot invertibility as well as the fact that quantum Lie group invariants are known not to do so. On the other hand, finite group invariants, such as the set of homomorphisms from the knot group to M_11, can detect knot invertibility. For many natural classes of knot invari

Greg Kuperberg

We present a definition of an invariant #(M,H), defined for every finite-dimensional Hopf algebra (or Hopf superalgebra or Hopf object) H and for every closed, framed 3-manifold M. When H is a quantized universal enveloping algebra, #(M,H) is closely related to well-known quantum link invariants such as the HOMFLY polynomial, but it is not a topological quan

Wayne R. Lundberg

A string-theoretic structure of the standard model is defined having a 4-D quantum gravity metric consistent with topological and algebraic first principles. Unique topological diagrams of string states, strong and weak interactions and quark families are evolved from this metric (but published separately). The theoretical structure includes known static and

Carlos C. Rodriguez

Completely automatic and adaptive non-parametric inference is a pie in the sky. The frequentist approach, best exemplified by the kernel estimators, has excellent asymptotic characteristics but it is very sensitive to the choice of smoothness parameters. On the other hand the Bayesian approach, best exemplified by the mixture of gaussians models, is optimal

Spiros A. Argyros, V. Felouzis

It is shown that every Banach space either contains $\ell ^1$ or it has an infinite dimensional closed subspace which is a quotient of a H.I. Banach space.Further on, $L^p(λ)$, $1<p<\infty $, is a quotient of a H.I Banach space.

Aleksandrs Mihailovs

The main result of this article is the decomposition of tensor products of representations of SL(2) in the sum of irreducible representations parametrized by outerplanar graphs. An outerplanar graph is a graph with the vertices 0, 1, 2, ..., m, edges of which can be drawn in the upper half-plane without intersections. I allow for a graph to have multiple edg

E. Alvarez, P. Meessen, T. Ortin

In order to study the discrepancy between the supersymmetry bound and the extremality bound for rotating black holes, the effect of duality transformations on the class of stationary and axially symmetric string backgrounds, called the TNbh, is considerd. It is shown that the Bogomolnyi bound is invariant under those duality transformations that transform th

Michael B. Green

This article reviews the non-perturbative structure of certain higher derivative terms in the type II string theory effective action and their connection to one-loop effects in eleven-dimensional supergravity compactified on a torus. New material is also included that was not presented in the talks.

J. Cruz, D. J. Navarro, J. Navarro-Salas

We investigate the canonical equivalence of a matter-coupled 2D dilaton gravity theory defined by the action functional $S = \int d^2x \sqrt{-g} (Rϕ+ V(ϕ) - 1/2 H(ϕ) (\nablaf)^2)$, and a free field theory. When the scalar field $f$ is minimally coupled to the metric field$(H(ϕ)=1)$ the theory is equivalent, up to a boundary contribution,to a theory of three

J. Lykken, E. Poppitz, S. P. Trivedi

We consider a brane configuration consisting of intersecting Neveu-Schwarz five-branes, Dirichlet four-branes, and an orientifold four-plane in a C^2/Z_3 orbifold background. We show that the low-energy dynamics is described by a four dimensional gauge theory with N=1 supersymmetry and SO(N+4) X SU(N) or SP(2M) X SU(2M+4) gauge symmetry. The matter content o

S. Deser, A. Gomberoff, M. Henneaux, C. Teitelboim

We discuss dyons, charge quantization and electric-magnetic duality for self-interacting, abelian, p-form theories in the spacetime dimensions D=2(p+1) where dyons can be present. The corresponding quantization conditions and duality properties are strikingly different depending on whether p is odd or even. If p is odd one has the familiar eg&#39;-ge&#39;= 2

F. Gonzalez-Rey

The kinetic action of the N=2 Yang-Mills vector multiplet can be written in projective N=2 superspace using projective multiplets. It is possible to perform a simple N=2 gauge fixing, which translated to N=1 component language makes the kinetic terms of gauge potentials invertible. After coupling the Yang-Mills multiplet to unconstrained sources it is very s

Alan R. White

Deep-inelastic diffractive scaling violations have provided fundamental insight into the QCD pomeron, suggesting a single gluon inner structure rather than that of a perturbative two-gluon bound state. This paper derives a high-energy, transverse momentum cut-off, confining solution of QCD. The pomeron, in first approximation, is a single reggeized gluon plu

Ali Abbasabaddi, David Bowser-Chao, Duane A. Dicus, Wayne W. Repko

The process mu+ mu- --> H gamma, though small compared to the resonance process, could be observable at proposed muon colliders, given expected integrated luminosities. The apparently leading diagrams occur at tree-level, and are proportional to the Higgs-muon coupling. We show, however, that the one-loop contribution is comparable to the tree-level amplitud

S. Dawson

An introduction to the minimal supersymmetric standard model is presented. We emphasize phenomenological motivations for this model, along with examples of experimental tests. Particular attention is paid to the Higgs sector of the theory.

Joao Pulido, Ana M. Mourao

Using the data from SuperKamiokande, Kamiokande and Homestake solar neutrino experiments we derive an upper bound on the magnetic moment of the neutrino and find $μ_{ν_e}\leq(2.2-2.3)\times 10^{-10}μ_{B}$, within four different standard solar models. We assume equal magnetic moments for all neutrino flavours. This limit is obtained when neutrinos do not unde

Helmar Meier, Zlatko Halabuka, Kai Hencken, Dirk Trautmann

We calculate the production of relativistic antihydrogen atoms by bound-free pair production. The cross section is calculated in the semiclassical approximation (SCA), or equivalently in the plane wave Born approximation (PWBA) using exact Dirac-Coulomb wave functions. We compare our calculations to the equivalent photon approximation (EPA).

Richard Hong Tuan

As the number of loops goes to infinity Feynman $α$-parameters undergo a fixing mechanism which entails a gaussian representation for propagators in scalar field theories. Here, we describe this mechanism in the fullest detail. The fixed values are in fact mean-values which can be determined via consistency conditions. The consistency conditions imply that o

M. Knecht, E. de Rafael

It is shown that in vector-like gauge theories, such as QCD, and in the limit of a large number of colours Nc, the ordering pattern of narrow vector and axial-vector states at low energies is correlated with the size of the possible local order parameters of chiral symmetry breaking. This has implications on the underlying dynamics of spontaneous chiral symm

H. Nunokawa, A. Rossi, V. Semikoz, J. W. F. Valle

This talk summarizes some results of our recent work focusing on the possibility to test solar matter density fluctuations by the future Borexino experiment.

H. Nunokawa, J. T. Peltoniemi, A. Rossi, J. W. F. Valle

This talk summarizes our recent work which studied the impact of resonant $ν_e \toν_s$ and $\barν_e\to\barν_s$ ($ν_s$ is a sterile neutrino) conversions on supernova physics, under the assumption that the mass of the sterile state is in the few eV -cosmologically significant range.

Vladimir B. Kopeliovich

The chiral soliton approach (CSA) provides predictions of the rich spectrum of baryonic states with different values of strangeness for any baryon number B. In the sector with B=1 the well known octet and decuplet of baryons are described within CSA, and some exotic states are predicted. In the B=2 sector there are many predictions, but only few of them - e.

M. Genovese, J. -M. Richard, FL. Stancu, S. Pepin

Within the chiral constituent quark model of Glozman and Riska, we discuss the stability of heavy pentaquarks, i.e. hadrons containing four light quarks and a heavy antiquark. The spin-dependent part of the Hamiltonian is dominated by the short-range part of the Goldstone-boson-exchange interaction. We find that these systems are not bound, having an energy

Shinya Kanemura

We discuss the non-decoupling effects on the loop-induced $H^\pm W^\mp Z^0$ vertex in the general two Higgs-doublet model. The decay process $H^\pm \to W^\pm Z^0$ is analyzed at one-loop level and possible enhancement of the decay width is explored. We find that a novel enhancement can be realized by the Higgs non-decoupling effects with large mass differenc

Di Qing, Xiang-Song Chen, Fan Wang

A dynamical valence and sea quark mixing model is shown to fit the baryon ground state properties as well as the spin content of the nucleon. The relativistic correction and the $q^3{\leftrightarrow} q^3q\bar{q}$ transition terms induced by the quark axial vector current $\barψ\vecγγ^5ψ$ in this model space is responsible for the quark spin reduction.

J. D. Bjorken

The basic ideas underlying the production dynamics and search techniques for disoriented chiral condensate are described.

U. Baur

We discuss the measurement of the $WWV$ ($V=γ,\, Z$) gauge boson couplings in present and future collider experiments. The major goals of such experiments will be the confirmation of the Standard Model (SM) predictions and the search for signals of new physics. The present limits on these couplings from Tevatron and LEP2 experiments as well as the expectatio

M. -C. Chu, S. M. Ouellette, S. Schramm, R. Seki

We investigate the temperature dependence of the instanton contents of gluon fields, using unquenched lattice QCD and the cooling method. The instanton size parameter deduced from the correlation function decreases from 0.44fm below the phase-transition temperature $T_c$ ($\approx 150$MeV) to 0.33fm at 1.3 $T_c$. The instanton charge distribution is Poissoni

Y. Kikukawa, H. Neuberger, A. Yamada

A certain truncation of the overlap (domain wall fermions) contains $k$ flavors of Wilson-Dirac fermions. We show that for sufficiently weak lattice gauge fields the effective mass of the lightest Dirac particle is exponentially suppressed in $k$. This suppression is seen to disappear when lattice topology is non-trivial. We check explicitly that the suppres

D. Sudarsky, T. Zannias

The static spherically symmetric ``black hole solution&#34; of the Einstein - conformally invariant massless scalar field equations known as the BBMB ( Bocharova, , Bronikov, Melinkov, Bekenstein) black hole is critically examined. It is shown that the stress energy tensor is ill-defined at the horizon, and that its evaluation through suitable regularization

Dieter R. Brill, Deepak Goel

The standard General Relativity results for precession of particle orbits and for bending of null rays are derived as special cases of perturbation of a quantity that is conserved in Newtonian physics, the Runge-Lenz vector. First this method is applied to give a derivation of these General Relativity effects for the case of the spherically symmetric Schwarz

E. S. Corchero

Static solutions of white dwarfs with spherical symmetry and local anisotropy are studied in the post-Newtonian approximation. It is argued that the condition for equilibrium must be that the total energy is a minimum for given baryon number and the question whether there is local isotropy or anisotropy inside the star should follow from that condition, rath

Peter Heinzner, Luca Migliorini

Let G be a complex reductive group and K a maximal compact subgroup. If X is a smooth projective G-variety, with a fixed (not necessarily integral) K-invariant Kaehler form, then the K-action is Hamiltonian. Let M be the zero fiber of the corresponding moment map. It is well known that the quotient M/K is a complex space in a natural way. We prove that M/K i

L. Klapka

In this paper a functional definition of geodesics is introduced which allows to generalize the notion of a geodesic from smooth to topological manifolds. It is shown that in the smooth case the new definition coincides with the classical definition of geodesics of a linear connection. If the smoothness is not required, it is shown by an example that the new

Kun Yang, R. N. Bhatt

We study the spin-1 chain with nearest neighbor couplings that are rotationally invariant, but include both Heisenberg and biquadratic exchange, with random strengths. We demonstrate, using perturbative renormalization group methods as well as exact diagonalization of clusters, that the system generates ferromagnetic couplings under certain circumstances eve

Sandeep K. Joshi, Abhijit Kar Gupta, A. M. Jayannavar

We consider the scattering of electron by a one-dimensional random potential (both passive and active medium) and numerically obtain the probability distribution of Wigner delay time ($τ$). We show that in a passive medium our probability distribution agrees with the earlier analytical results based on random phase approximation. We have extended our study t

Sandeep K. Joshi, A. M. Jayannavar

We report a detailed and systematic numerical study of wave propagation through a coherently amplifying random one-dimensional medium. The coherent amplification is modeled by introducing a uniform imaginary part in the site energies of the disordered single-band tight binding Hamiltonian. Several distinct length scales (regimes), most of them new, are ident

Sandeep K. Joshi, A. M. Jayannavar

We consider the scattering of an electron from a semi-infinite one-dimensional random medium. The random medium is characterized by force, $-\d V/\d L$ being the basic random variable. We obtain an analytical expression for the stationary delay time ($τ$) distribution $P_s(τ)$ within a random phase approximation. Our result agrees with earlier analytical exp

T. P. Pareek, Sandeep K. Joshi, A. M. Jayannavar

In mesoscopic systems to study the role of inelastic scattering on the phase coherent motion of electrons two phenomenological models have been proposed. In the first one, due to Büttiker, one adds a voltage probe into the system (or in the scattering matrix). The second model invokes the complex (or optical) potential in the system Hamiltonian. Studying a s

Fabio Bernardini, Vincenzo Fiorentini

Ab initio electronic structure studies of prototypical polar interfaces of wurtzite III-V nitrides show that large uniform electric fields exist in epitaxial nitride overlayers, due to the discontinuity across the interface of the macroscopic polarization of the constituent materials. Polarization fields forbid a standard evaluation of band offsets and forma

Victor Romero-Rochin, J. Miguel Rubi

Using an interpolant form for the gradient of a function of position, we write an integral version of the conservation equations for a fluid. In the appropriate limit, these become the usual conservation laws of mass, momentum and energy. We also discuss the special cases of the Navier-Stokes equations for viscous flow and the Fourier law for thermal conduct

O. J. O&#39;Loan, M. R. Evans, M. E. Cates

We present a driven diffusive model which we call the Bus Route Model. The model is defined on a one-dimensional lattice, with each lattice site having two binary variables, one of which is conserved (``buses&#39;&#39;) and one of which is non-conserved (``passengers&#39;&#39;). The buses are driven in a preferred direction and are slowed down by the presenc

V. Dananic, A. Bjelis

Reconsidering the variational procedure for uniaxial systems modeled by continuous free energy functionals, we derive new general conditions for thermodynamic extrema. The utility of these conditions is briefly illustrated on the models for the classes I and II of incommensurate-commensurate systems.

John Schliemann, Franz G. Mertens

We examine solitary waves in classical Heisenberg chains with an uniaxial anisotropy and a parallel magnetic field in a continuum approach. The boundary conditions commonly used are generalized to nonlinear spin wave states, which themselves turn out to be stable only for an anisotropy of the easy-plane type. In this case we obtain two different branches of

J. Bünemann, W. Weber, F. Gebhard

We introduce Gutzwiller wave functions for multi-band models with general on-site Coulomb interactions. As these wave functions employ correlators for the exact atomic eigenstates they are exact both in the non-interacting and in the atomic limit. We evaluate them in infinite lattice dimensions for all interaction strengths without any restrictions on the st

G. Wellein, H. Fehske

We present a detailed numerical study of the one-dimensional Holstein model with a view to understanding the self-trapping process of electrons or excitons in crystals with short-range particle-lattice interactions. Applying a very efficient variational Lanczos method, we are able to analyze the ground-state properties of the system in the weak-- and strong-

L. G. Tilstra, M. H. Ernst

The transfer matrix and matrix multiplication ansatz, when applied to nonequilibrium steady states in asymmetric exclusion processed and traffic models, has given many exact results for phase diagrams, bulk densities and fluxes, as well as density profiles and spatial and temporal correlation functions for models with a dynamics that is updated in (random) s